Interesting advice, thank y'all. If the flat isn't butter, I just must not be cooking it long enough. I guess I'm a bit gun shy after a couple of runs of some dry meat.

How do people get such juicy, tender brisket without wrapping/foiling at some point? I've had brisket at restaurants where they don't wrap at all and it's just moist and tender. I feel like there is some secret I don't know haha.

if you want tender moist & juicy cook it hot 300 is where I keep my grate temp +/-25 deg The longer that brisket sits at a low heat the easier it is to dry it out. When you cook L&S the meat goes through a stall the outside gets dry out while the inside tries to cook as the collagen and fat break down at different rates. This is the reason so many L&S cooks use foil. When you cook at higher temps there is no stall the temp steadily rises and the collagen breaks down and the fat renders at the same rate.
If you have ever made jerky you keep your temps at around 170 to dry out a thin strip of meat. Cooking a brisket at 225 is not much different in relation the the thickness. The difference between 225 and 250 is about the same as 170 is to 225, 250 is a little better but you will still have a stall while surface drying will be slightly reduced. Once you get to 275 there is a small stall and you can get by without foil.and your cooking time will drop into the 45-50 min a lb zone. At 300 the time drops to 30-40 min per lb the bark will be firm and te fat fully rendered.
Some H&F Flat Shots from a few packers